@Mrdon - While you can use a 3D printer for some of the components, some parts have to be made of metal. These parts include springs, bolts, upper receivers/slides, firing pins and finally, barrels. There are no polymers strong enough to be used for these parts. While some components in a gun can be made from plastics, we are a LONG way off from a plastic gun that can be printed over the weekend and sold on Monday. In addition, even if you could "print" a gun, you still have to feed it. You can't print ammunition.

There's an often quoted line that guns don't kill people... etc. In support of that is that in Switzerland almost every male over 18 has a rifle and ammunition (if they went to the army) as part of that country's defence policy. They have a significantly lower crime rate with guns than most other countries. This seems to support the initial quote. But when you combine guns with a society such as that in the US with almost no social justice and an incredible gulf between the richest and poorest, you really have a disaster waiting to happen, and so often it has. The guns certainly don't kill the people but the almost free availability of them makes it really easy to commit crimes with them, and when comapring a gun to screw driver as one reader has, a gun with a 20 shot magazine can easily kill 20 people at many metres without any hope of the victims being able to fight back regardless of strength, where as a perpetrator with a screw driver can only kill those within reach and less strong than him/herself. That to me says that removing guns can put a serious dent in the crime statistics. That said, creating an environment where social justice prevails will be far more effective at reducing crime with guns. Now with all of that said, and getting back to the original article, a technology about to become ubiquitous (3D printing) would in the presence of freely available CAD files and in the absence of social justice make matters horrendously worse I believe. There are similar threats conceivable through availability of on-line ordering of gene fragments and papers describing how mutant bacteria was created by researcher xyz when that fall into the hands of a would be terrorist. It's nice to have freedom, but it always comes at a cost, and it has to be an amount we are willing to pay. Just my 2 bob's worth. This is of course MY opinion, and one thing we should all defend is the right to all to have an opinion and the right to voice it.

@MYRONB: I couldn't agree with you more. That is in fact why I choose to write about Michael Guslick's project--not because of my political feelings for or against gun control, but because he is an engineer pushing the boundaries of technology for purposes of advancing engineering. I knew when examined through that lens, the project was newsworthly and would be of interest to the Design News audience.

The majority of engineers of all stripes seem to favor guns. I think it has to do with rational thinking, or perhaps even Libertarian thought. When I worked for a major DOD contractor in Colorado there was always a fight in the engineering departments (software and hardware) in who could be gone during black powder, early, or late elk season. I usually opted for either black powder or early season and would hunt with guns that I made myself by hand. I may, or may not have broken federal law by giving my dad a flintlock rifle and pistol for his 54th birthday in 1976. He treasured them, and when he passed away in 1992 my mother gave them back to me. As far as making them, I could build nearly any type of firearm, including machine guns with nothing more than a lathe equiped with milling attachments. But why would I want to make something I have no use for? They are pretty much useless as even our military has found. The M16 now shoots 3 round "bursts". When I was a young GI they were full automatic, dumping the 20 round magazine in a heartbeat. An 8 inch screwdriver in the brain is as fatal as a gunshot, yet moral people are not willing to inflict such things on other humans.

3D printing is no threat to anyone unless one gets their fingers pinched by the stepper motor. All tools can be dangerous.

Hi Byron,
I agree with you about the gun's innovation and engineering but there are social and political ramifications to "homebrewing" weapons. With no traceability of a 3D printed gun, an ample supply can be made on the weekend and sold on the streets Monday morning. If a crime is committed with the gun, there's no way to identify the weapon because it was manufacturered on a 3D printer. Importantly, children would have access to online CAD files and 3D printers and you know the implications to that scenario.

I don't mind that the blogs are filled with political/social/political discussions because engineers don't (or shouldn't) live in a vacuum bounded by technical subjects only, while remaining innocent (ignorant) of life' realities. In this, case I am inclined to celebrate Engineer Michael Guslick's ingenuity for using a 3-D printer to make rifle receiver, rather than join the anti-gun brigade lined up to crucify the guy for his choice of 3-D printing project.

Just suppose that Guslick himself, or another engineer inspired by his work, used Guslick's 3-D experience to work with a molecular biologist or medical specialist using an appropriate medium and cellular material to build tissue and organs, perhaps to defeat cancer or other serious diseases. In my humble opinion, I think Guslick and others like him should be encouraged because the potential good far outweighs the any imagined downside.

If 17th century naysayers had their way, Jean de Hautefeuille never would have proposed an early form of internal combustion engine using gunpowder as a fuel, nor would Christaan Huygens (a very bright guy in several other fields) have built and demonstrated a gunpowder-powered rudimentary I.C. engine to pump water. Their pioneering work perhaps in some way inspired the later work of Lenoir, Otto, and Diesel who followed up with the internal combustion engine pretty much as we know it to day.

I'm interested in the developing 3D printing technology, and was naturally interested in the story. The use of terminology was unfortunately sloppy.

It wasn't an AR-15. It wasn't an automatic rifle. It wasn't even a rifle.

It was a .22 caliber pistol built on the platform of an AR-15 lower receiver. You'll see a commercial version of something like this at almost every gun show. That's not unique. As the article rightly stated, the novelty was the way the receiver was made.

The reactions were funny and surprising to me, for a bunch of engineers. As was pointed out, anyone with a home milling machine or bench top drill press can make a fully legal AR-15 out of aluminum. I made one on a Sherline, surely one of the smallest metal mills out there. An AR lower has been made from a plastic cutting board (HDPE). Again, the only novel thing here was the way the receiver was made.

The AR-15 (AR is short for Armalite Rifle, not automatic rifle, and not assault rifle - Armalite developed the design in the 1950s) is probably the most popular sporting rifle in American hands. I've heard that well over 10 million are in civilian hands, but can't back that number up. Again, they are for sale everywhere; they're sold in Walmart. Like every other manmade object they are completely amoral - neither good nor bad; that can only lie in the human that uses it. The recurring idea that guns are only used for killing is also absurd to recreational shooters. Of the many millions of AR-15s out there, the vast, vast majority have never been shot at anything other than paper targets at a range. As for making up karma for building one, I wasn't aware paper targets had a soul. I have shot a lot of paper plates and printed paper.

Would people have been as upset if the post had been about printing a major component of a crossbow or compound bow? I sure wouldn't want to get shot by a broadhead arrow, but I know there are archery clubs and archery competitions all around the country. Why the difference?

Well, Dave, you've got a point, BUT I have to take exception to that in a way. I've read these blogs for quite some time, and the focus of MOST of them IS the item under scrutiny, and nothing else! So, because this particular discussion involved a "hot-button" issue of modern society, the tangents became the focus. I can't agree with that logic.

By that reasoning, if someone wrote in about a machine that collates Bibles, and some engineers in this group are atheists, then the tangential discussion should spin off to a discussion of whether God exists???

I maintain that if one wants to get onto their soapbox about some current issue, then by all means, go to a social network, or "like me" outlet, and have at it! That's the beauty of the American experience ... .we CAN express our own opinions in a public forum WITHOUT fear from censorship.

I, too, was raised in a major metropolitan area where "gun control" was extremely harsh, yet the murder rate was much higher than other cities of other states which had more sensible approach to firearms control. Whenever I get tangled up into this issue, I always cite one example, Switzerland. There, EVERY able-bodied citizen MUSt be proficient in firearms use, and MUST own a rifle to defend his/her country! And, what is the crime/murder rate there?? A miniscule part of 1%. In fact it's so low that the records are hardly kept.

@OLD_CURMUDGEON: It's unrealistic to try to separate the technical aspects of a topic from its social, environmental, economic, or ethical aspects. All of these aspects come together in a single whole, which we call "reality." As engineers, we have a professional responsibility to think about the broad consequences and implications of our work. I don't agree with Beth, but I appreciate her willingness to consider the societal implications of a technical topic.

I grew up in the city of Chicago, which has some of the toughest gun laws in the country. Even so, two of my friends were shot and killed while I was in high school. In my first job, at a church-run immigrant center, I regularly found bullet casings while sweeping the sidewalk. In contrast, my dad grew up in rural Michigan, where there were guns in nearly every home, yet shootings were unheard of. So I am very skeptical of the relationship between violence and legal access to guns. The root causes of violence are far more complex.

A few weeks ago, Ford Motor Co. quietly announced that it was rolling out a new wrinkle to the powerful safety feature called stability control, adding even more lifesaving potential to a technology that has already been very successful.

It won't be too much longer and hardware design, as we used to know it, will be remembered alongside the slide rule and the Karnaugh map. You will need to move beyond those familiar bits and bytes into the new world of software centric design.

People who want to take advantage of solar energy in their homes no longer need to install a bolt-on solar-panel system atop their houses -- they can integrate solar-energy-harvesting shingles directing into an existing or new roof instead.

Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.